1. Field of the Invention
The present invention relates to inspection and review of substrates using electron beam imaging.
2. Description of the Background Art
In a conventional electron beam inspection instrument, a manufactured substrate (such as a silicon wafer or a reticle) is scanned with a focused beam of electrons which results in the emission of electrons, including secondary and/or backscattered electrons, from the substrate surface. The emitted electrons are detected, and the detection data is typically converted into an image of the surface of the specimen. The image is typically from a “normal” view (i.e. a view from a perspective perpendicular to the surface). These images are then analyzed numerically to detect abnormalities (referred to as defects) in the manufactured substrate.
Furthermore, the detected defects may be reviewed by further imaging and classified, either manually or automatically, into different classes or categories. The classification of a defect may be used to determine its cause such that appropriate adjustments may be made in the manufacturing process so as to improve its yield.
It is highly desirable to improve methods and apparatus for electron beam inspection. More particularly, it is highly desirable to improve the classification of defects imaged by electron beam instrumentation.